There are a variety of industrial applications utilizing injection of a jet of gas into a reaction space.
One application is a non-ferrous metallurgical furnace. It is known to provide a layer of liquefied inert gas such as Argon over a bath of molten for the purpose of avoiding the pickup of oxygen from the atmosphere above the bath. The Argon is typically introduced above the bath as a stream of liquefied gas. The liquefied gas pools above the bath and vaporizes to produce an expanding gas which drives out any oxygen above the surface of the bath. Typically, the Argon is introduced above the bath using a fixed lance. While the prior art methods have provided a fairly satisfactory solution, such methods utilizing a fixed lance do not achieve maintenance of a uniform layer of liquefied gas above a large area of the bath while at the same time avoiding overconsumption of the Argon.
Some non-ferrous processes utilize oxygen for refining. An example is the refining of copper. Copper is inert relative to other metals so oxygen and/or air can be used to oxidize dissolved elements. Oxygen and/air can also be used to impart the correct amount of dissolved oxygen for certain applications such as copper rod. Non ferrous baths often have a large surface area that would normally be poorly mixed. A moveable lance would provide more uniform application of oxygen and/or air.
Another application is a furnace, including electric arc furnaces (EAFs). In electric arc furnaces, the materials to be melted are introduced at the top of the furnace. Depending on several parameters as type of raw materials (pig iron or scrap iron or steel), size of the furnace, etc, the EAF may be equipped with burners delivering a power of several megawatts. This combustion of fuel (mainly natural gas but sometimes fuel-oil) with oxygen brings heat to initiate melting of the scrap. The scrap in front of the burners is heated first. The burner must have a high momentum flames for at least a few reasons. First, high momentum flames are needed to avoid the deviation of the flame towards the walls or even towards the burner panel. Second, they are needed to quickly create a cavity in the scrap pile thereby increasing heat transfer efficiency. Third, they are needed to avoid clogging of the injectors by steel droplets once the scrap is melted and transformed into liquid steel (thus, a low power flame is always on).
A cutting operation in the electric arc furnace occurs during the scrap melting phase when the scrap is hot but not molten. In this phase, heat transfer between oxy-fuel burner flame and the scrap is no longer efficient so final melting in the “cold spots” is performed using oxygen and the mechanism of heating is chemical energy provided by the oxygen reacting with the scrap. Cutting is used normally by operating oxy-fuel burners with excess oxygen or by using the door lance through the slag door.
A refining operation in an electric arc furnace deals with the removal of primarily carbon, but also phosphorus, sulfur, aluminum, silicon and manganese from the steel. Typically, refining operations are carried out once the steel scrap is completely melted and involves oxidation of the above mentioned impurities through injection of a supersonic oxygen jet into the molten bath. Removal of carbon impurities is referred to as the decarburization process, a process which occurs in the steel bath and in a slag-gas-steel emulsion after the burner operation is stopped. The refining step in the EAF is also called the “hard lance mode”. It includes reactions between C (coal particles and dissolved carbon in the melt), CO, CO2 and O2 which provided by the supersonic lance. The oxidation of carbon generates CO bubbles that can flush from the bath dissolved gases such as hydrogen and nitrogen, which are also recognized as a concern. The injected oxygen also lowers the bath carbon content to the desired level for tapping. Because most of the other non-carbon impurities during refining have a higher affinity for oxygen than carbon, oxygen preferentially reacts with these elements to form oxides which can be removed in the resultant slag.
The location of an EAF tool such as a burner or lance can be described by the distance of the tool from the nominal steel bath surface. The lance is typically located a distance of 0.5 to 2 meters above the steel bath. A foaming slag (CO bubbles), created by the carbon-oxygen reaction during carbon injection, floats on the steel bath. In most EAFs, a burner and a supersonic lance are combined into a single multifunction tool. The implementation of such a tool depends mainly on the furnace type, the composition and quality of the raw materials. The angle of injection (with respect to horizontal) of the supersonic O2 jet is often around 40-45° from the horizontal. However, this value can be as high as 50° and it will depend upon the construction of the furnace. Once installed to a furnace, many supersonic lances for EAFs currently available in the market inject oxygen into the bath at a fixed angle. This fixed angle present several limitations. The fixed location of impact of the supersonic jet locally depletes the carbon content in the impact area. As, a result, FeO generation in the immediate vicinity of the impact point is relatively high. FeO is very corrosive to furnace refractories, so excessive refractory damage at this location is common. Second, due to certain technical constraints, many lances have to be located at a distance higher than optimal above the steel bath surface to achieve the often optimal 40-45° angle of injection. This is because the jet must be tilted more downwardly toward the steel. Third, fixing this angle has the effect of fixing the area of the steel bath surface that is targeted by the supersonic jet. If only a portion of the bath can be stirred by impingement of the jet upon the targeted portion, the overall refining reaction is limited by the relatively slow diffusion of oxygen through the non-targeted/unstirred portions of the bath. Acceleration of the overall refining process thus often requires the use of multiple tools for separately targeting multiple portions of the bath. Fourth, apart from the stirring issue, a fixed angle of attack limits the ability of the lance to generate a thick foamy slag on the bath surface over more than just the targeted area. This is important because quick generation of thick, foamy slag across much of the bath surface decreases the tap-to-tap time and increases furnace productivity. Speedier generation of the thick, foamy slag often requires the use of several lances each one of which targets a specific portion of the bath.
As a result of the fixed angle, most of the existing supersonic lance solutions are concerned with estimating an optimal number of lances and determining their optimal locations. While a more dynamic and adaptive control may be achieved with the use of supersonic lances utilizing moving parts, this approach is not a robust solution for supersonic jets in the very dusty environments of EAFs because the moving parts are exposed to severe thermal, mechanical and chemical attacks.
Similar rationales can be applied to other steelmaking processes such as the Basic Oxygen Furnace (BOF), the top and bottom mixed blowing converter (QBOP), the Argon Oxygen Decarburisation (AOD) process and the Vacuum Oxygen Decarburization (VOD) process.
Thus, there is a need in the art for providing a solution that overcomes the above problems.